The invention is concerned with a door lock, in particular for doors, tailgates or hoods of motor vehicles, having a lock latch which can be pivoted between a position releasing a locking peg and a position locking the latter, a detent pawl which can be moved between a locking position arresting the lock latch and a position releasing the lock latch, and a motor-driven, circulating driving pin which, when the drive is switched on, carries the detent pawl along in its path into its position releasing the lock latch and then runs against a stop which retains the detent pawl, which is situated in its position releasing the lock latch, in a position which blocks the driving pin.
A door lock of this type, as is described, for example; in DE 195 05 779 Al, offers the possibility of switching off the electric driving motor, after the lock latch is released, by monitoring the current consumption of the motor if the driving pin runs against the stop and the current consumption rises as a consequence of the blocked motor. An electronically monitored switching-off means of this type operates more reliably than microswitches which are susceptible to faults.
In the case of the door lock described in DE 195 05 779 Al, the stop is provided directly on the detent pawl. Although this solution manages with relatively few parts, there are, limitations in this design, in the spatial arrangement which, under some circumstances, make adaptation to a predetermined constructional space more difficult.
The object of the invention is to provide a door lock having an opening aid, said lock permitting a more flexible spatial design.
According to the invention, the object is achieved by a door lock of the type described at the beginning, in which the stop is arranged on a blocking lever which is mounted separately from the detent pawl and can be carried along into its blocking position by the detent pawl as it is being shifted into the position releasing the lock latch.
The solution according to the invention offers the advantage that a more flexible spatial arrangement of the individual components is possible on account of the separately mounted blocking lever and the simplified detent pawl. As a result, adaptation of the door lock to particular spatial conditions and limitations in constructional space, as can frequently be encountered precisely in the automobile sector, is considerably simplified. In addition, there is the possibility, by varying the center of pressure, of providing a transmission ratio between the detent pawl and the blocking lever which can be used to influence the interaction between the blocking lever, the running-on driving pin and the detent pawl in order to reduce the forces which occur.
In a preferred embodiment of the invention, provision is made for the driving motor to drive a driving element which can be rotated counter to the force of a spring in a certain angular range relative to a driving disk which is arranged on the same rotational axis and on which the driving pin is arranged eccentrically.
The relative rotatability between the driving element and driving disk counter to the action of the spring avoids under all circumstances, when the electric driving motor has a defect, blocking of the detent pawl which could result in the affected lock no longer being able to open or no longer being able to close. Depending on the position in which the driving pin stops, it is moved by the prestressed spring into a position in which the detent pawl can be moved freely, or in the case of manual emergency opening, for example, the detent pawl can press aside the driving pin, lying in the way, counter to the force of the spring.
In a further, preferred refinement, provision is made for a compression spring to be arranged in a spring channel, which is open on one side, on the driving element or the driving disk and to be supported against a stop on the respective other component. Such an arrangement of the compression spring can be fitted easily, particularly low manufacturing costs arising if the driving element and the driving disk are manufactured from plastic and the spring channel and the stop are formed integrally on the respective component. Under some circumstances, the driving pin may also be manufactured from plastic, but at higher loads a driving pin made of metal or a pin which is provided with a metal coating in the region of the contact surface with the detent pawl and the stop is advantageous. Prestressing of the spring may be expedient, also for improving the grip of the spring in the spring channel.
Furthermore, a second stop is preferably provided which interacts with the rear wall of the spring channel and limits the relative rotatability between the driving element and the driving disk counter to the prestressing direction of the compression spring. This second stop ensures that undefined relative positions which might be disadvantageous for the functioning are unable to occur between the driving element and the driving disk.
It has proven expedient for the spring channel, in a simple design, to extend over an angular range of approximately 90xc2x0 and to be limited by two lateral, circular-arc-shaped walls. The angular range of 90xc2x0 of the extent of the spring channel allows prestressing of the compression spring situated in it by approximately 45xc2x0, an angular range which has proven particularly expedient in order to avoid malfunctions.
In order to improve the functioning capability of the door lock, it is of advantage for the lock latch to be prestressed by a spring in the direction of its open position and/or for the detent pawl to be prestressed by a spring in the direction of its position arresting the lock latch. While the lock latch can be moved during the closing of the tailgate of the vehicle, for example, into its closed position counter to the force of the restoring spring by the locking peg, the detent pawl is moved counter to the force of its restoring spring into its position releasing the lock latch. In the closed position of the lock latch, the latter is supported against a latching means on the detent pawl under the load of its prestressed spring, while when the lock latch is opened, the detent pawl is supported against a correspondingly shaped stop on the lock latch.
A particularly simple embodiment makes provision for a single spring between the lock latch and the detent pawl to prestress both elements.